Orcutt, Santa Barbara County, California, USA May 26, 2014 Size: ~2mm
This wasp was attacking aphids on a cherry tree. Someone (https://www.flickr.com/photos/44150996@N06/14101666270/) ID'd it as Alloxystini (Cynipoidea, Figitidae, Charipinae ) on my flickr page, it would be a new tribe for the guide if someone can confirm